All our PHP application stacks (like WordPress, Drupal, Joomla! among others) use the latest stable version of PHP 5.4 currently, so it is not necessary to upgrade those.
The BitNami Red Hat-based Amazon Cloud Images were also affected by this issue. We have removed older versions of BitNami apps published on the Amazon Cloud catalog and marketplace that may be vulnerable to this security issue. We continue working on releasing all new Red Hat images for all BitNami applications.
If you are using a Red Hat BitNami cloud image, the new PHP version is available in the Red Hat repositories:
$ sudo yum update
That will update your system and upgrade your current PHP installation to the one that includes the security fix.